Assembly diagram of the gear control pistons on gearbox — plan E806-2309 (Védie, 1957)

In this document

This technical plan, referenced E 806-2.309, presents the « SCHÉMA de MONTAGE des PISTONS de COMMANDE de VITESSE sur B.V. Solution cylindres en 2 parties » p. 24.

Parts list

The drawing details two sets of coaxial cylinders, in cross-section:

Other elements are mentioned: the fork shafts and the gearbox cover p. 24.

An adjustment indication appears clearly in the centre of the diagram: « RÉGLAGE BOÎTE 4mm », associated with the note « Longueur réelle du piston » p. 24. The plan is drawn at a 2/1 scale.

The title block specifies that this plan is « VALABLE POUR ESSAI 42.806 », launched by the note bearing the number E806-2200, and signed by Védie on 8-3-57 p. 24. The "REMPLACE PLAN" field is not filled in, and the approval visa remains illegible.

Context

This type of plan is part of the developments carried out at the Citroën design office regarding the hydraulic systems of the DS, of which Paul Magès was one of the major contributors. The hydraulically operated gearbox control cylinders contributed to the servo-control device that characterised the mechanical sophistication of the model.

The "E806" numbering suggests a series of tests or technical assemblies specific to this mechanism, distinct from the "D314" and "DS 314" references found on other plans in the same collection, relating to the clutch release cylinder.

Archivist's perspective

This plan dated 8 March 1957 seems to constitute an evolution or a variant of an earlier assembly: the mention "solution cylindres en 2 parties" p. 24 suggests that a single-part alternative solution existed, or was being considered — information however not confirmed by this document alone.

The precision of the "4 mm gearbox" adjustment and the note on the actual length of the piston p. 24 testify to the care taken with manufacturing tolerances, a characteristic of the adjustment work specific to the hydraulic systems developed by Magès' team.

This document can be related to the Handwritten insert "54 to 57 — Piston, clutch release cylinder", which covers the same period and the same types of components, as well as with the Plan of the DS 314-02 clutch release cylinder (1957), contemporary and belonging to the same design workshop.